Phone tab strips: compact-verb follow-ups

Found while visually checking Task 7238 (list tab strips at 390px with `compactActions` + `ui/CompactVerb`). - Slots: the pool's Add slots toggle shows the word "Close" on a phone while open. Give the open state a compact glyph (e.g. ✕), so the strip row keeps the same width open or closed. - Brains and Projects beside an open detail still use their own '+' (`COMPACT_ADD_SX`) next to the newer `CompactVerbLabel` ＋. Fold them into one compact-verb mechanism. - Agents and Catalog reserve a 44px verb slot on a phone even for a reader with no verb. Drop the slot when no tab of the strip can ever carry a verb for this viewer. - On a phone, the Playbooks "Preview" chip and the Customers "Test mode" chip are hidden to keep the strip on one row. Give each status a phone home, e.g. a line at the top of the panel. - Brains' Share button on a phone reads only "Share", next to Add account. Give it an accessible name that says what it shares. - Support: the sort control (⇅) sits alone on its own row at the top of the panel on a phone. Put it beside the list's first row or into the filter strip. - Customers: the filter strip stacks five dropdowns over about three rows at 390px. Collapse the secondary filters behind a filter menu on a phone, as Tasks does. Out of scope: desktop layouts; Billing (done in Task 7238). Done means: - At 390px each item above is fixed and checked visually on the live stack.

Fixed all 7 phone tab-strip items at 390px (item 5 was already shipped by Task 7314) and checked them visually. Quick gate and 1833 changed-area tests green. PR #5972 merged by the lane; Jaah Deploy succeeded. Follow-ups filed as draft #7371.